Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already establish read-only, idempotent, non-destructive behavior. The description adds material context not in annotations: the operation is free and avoids paid routes, which matters on a paid API server. It does not detail auth or rate limits, but that is not critical for a read-only catalog.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Single sentence, front-loaded with the [FREE] marker and core purpose. Every phrase contributes: catalog scope, included price/description metadata, and the no-paid-route constraint.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a zero-parameter, read-only catalog endpoint with no output schema, the description supplies the catalog scope, included metadata, and free/no-paid-route behavior. Annotations cover safety traits, so no necessary context is missing.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Zero-parameter schema with 100% description coverage; baseline is 4. No parameter meaning needs to be conveyed, and the description does not need to compensate for schema gaps.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb ('Returns'), specific resource ('full tool catalog'), included metadata ('prices and descriptions'), and a clear differentiator ('without calling any paid route'). This cleanly separates it from paid endpoint siblings and preview variants.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Signals when to use it via '[FREE]' and 'without calling any paid route', implying it is the discovery step before invoking paid routes. It does not explicitly name alternative discovery tools, but the routing condition is clear.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.